y'know by 'all equipment' I thought it meant he just has his standard set, not the optional equipment and artifacts other than pure hearts also, haha
either way, this makes for a much more tougher matchup than previously expected.
the power nullification for mario has only been shown to nullify invulnerability it seems, so im not sure if it could a universally nullify any ability, especially something like the SAVE system. Catch Cards probably wouldn't do much, Chara's immune to SOUL manipulation and if they are sealed they could just load back to a certain SAVE point.
The AE1 for chara is a point of interest as well, even if it is under a 'possibly' it still should be acknowledged as an ability in chara's moveset, Chara quite literally became the feeling of the players statistics increasing, mario would have to somehow interact with the abstraction itself to effect chara, somehow.
so, If mario is truly unable to interact with AE1 than chara I feel still gets a win here, and even then, I dont think he could still counter the SAVE system in any effective way as I mentioned in my previous points above.